These set of button animations were designed by Yugam hey use CSS-Masks to achieve these experimental effects. The first hover effect feels like smoke being cleared out to reveal the content below, the second effect feels like erasing the layer from the top with a big brush and the final effect feels like liquid being absorbed into a sponge.
If you are having trouble with the pen, try the archived copy on GitHub
Smoke and Liquid Effect Snippet
See the Pen CSS-Mask Button Hover Animation ( Experimental ) by Yugam (@pizza3) on CodePen.0